This invention relates to a series of dihydropyrazolopyrroles which are selective inhibitors of phosphodiesterase (PDE) type IV or the production of tumor necrosis factor (TNF), and as such are useful in the treatment of, respectively, inflammatory and other diseases; and AIDS, septic shock and other diseases involving the production of TNF.
This invention also relates to a method of using such compounds in the treatment of the above diseases in mammals, especially humans, and to pharmaceutical compositions containing such compounds.
Since the recognition that cyclic adenosine phosphate (AMP) is an intracellular second messenger, E. W. Sutherland, and T. W. Rail, Pharmacol. Rev., 12,265, (1960), inhibition of the phosphodiesterases has been a target for modulation and, accordingly, therapeutic intervention in a range of disease processes. More recently, distinct classes of PDE have been recognized, J. A. Beavo et al., TiPS, 11,150, (1990), and their selective inhibition has led to improved drug therapy, C. D. Nicholson, M. S. hahid, TiPS, 12, 19, (1991). More particularly, it has been recognized that inhibition of PDE type IV can lead to inhibition of inflammatory mediator release, M. W. Verghese et al., J. Mol. Cell Cardiol., 12 (Suppl. II), S 61, (1989) and airway smooth muscle relaxation (T. J. Torphy in "Directions for New Anti-Asthma Drugs," eds S. R. O'Donnell and C. G. A. Persson, 1988, 37 Birkhauser-Verlag). Thus, compounds that inhibit PDE type IV, but which have poor activity against other PDE types, would inhibit the release of inflammatory mediators and relax airway smooth muscle without causing cardiovascular effects or antiplatelet effects.
TNF is recognized to be involved in many infectious and auto-immune diseases, W. Friers, FEBS Letters, 285, 199, (1991 ). Furthermore, it has been shown that TNF is the prime mediator of the inflammatory response seen in sepsis and septic shock, C. E. Spooner et al., Clinical Immunology and Immunopathology, 62, S11, (1992).